Donald Trump, his family and the Trump Organisation have filed a lawsuit against Deutsche Bank and Capital One in an attempt to stop them releasing financial and banking records to Congress.
The lawsuit, filed on Monday in a Manhattan court, argues that the subpoenas issued for documents by two Democrat-controlled congressional committees overstepped the mark and should not be acted on.
Deutsche Bank was a longtime lender to Mr Trump before he took office. The US president’s sons Donald Jr. and Eric and daughter Ivanka also put their names to the lawsuit.
The development escalates a battle between the Democrats, who now control the House of Representatives, and the White House, which is opposing some demands for documents and witnesses.
The House’s Intelligence and Financial Services Committees both recently issued subpoenas to Deutsche Bank as part of an investigation into Mr Trump’s finances.